1983 300SD electrical problems - Mercedes Forum - Mercedes Benz Enthusiast Forums

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Old 09-22-2006, 07:19 PM
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Join Date: Sep 2006
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Default 1983 300SD electrical problems

Hi all,

I have had my 1983 300SD for about a year now, and it has always had electrical quirks, mostly intermittent problems. Windows/sunroof working and then not working, mostly. About 2 months ago the backlight on the dash went out. It came on for about a week maybe a month ago, then quit again. Recently, the entire dash--all the gauges and lights--started cutting out altogether, then coming back on randomly. Today, though, the signals and taillights have gone for a crap. It started as an intermittent thing, but now they are out and have not worked for a few hours. I swapped some of the fuses around to see if that was the problem, but it doesn't seem to make a difference. When I shut the engine off and checked the 4-ways, they worked fine, but when I checked the signal lights, they do not work and there was a strange clicking under the hood, which seemed to be coming from the fuel filter housing. Now, when I start the engine, the gauges and dashlights all come to life, but shut off when I turn on the signal.

I am quite concerned because I have no tail or signal lights, which is obviously not safe to drive. I am not totally technically savvy on this machine, but I do have a basic understanding of auto mechanics, and do exceptionally well at following instructions.

Any help that anyone can provide would be immensely appreciated!
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Old 09-23-2006, 01:30 PM
Join Date: Aug 2005
Posts: 86
Default RE: 1983 300SD electrical problems

It sounds to me like a bad ground or faulty relay. Try swapping the relays around in the fuse box. Make sure they are like kind. Also, check the connection for the guages behind the instrument cluster. It pulls straight out, no screws, careful of the oil pressure line. Look carefully under the fuse box for mice damage.
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Old 09-25-2006, 03:48 PM
Join Date: Sep 2006
Posts: 4
Default RE: 1983 300SD electrical problems

Man, I hear ya! I'm having the same or at least similar difficulties. My gauges go dead when I brake, signal a turn, open a window. Sometimes they come back, sometimes not. Glow pulg light comes on occasionally when this happens. Everything stays dead for a while. Don't know about brake lights. I just go faster and hope to leave my problems behind. Would appreciate anything that anyone can tell us....
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Old 09-25-2006, 03:57 PM
Join Date: Aug 2005
Posts: 86
Default RE: 1983 300SD electrical problems

Another thought I had......some time ago, my brake light switch fried, it caused a short and all kinds of crazy problems. Good luck...
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Old 09-28-2006, 06:08 AM
Join Date: Sep 2006
Posts: 2
Default RE: 1983 300SD electrical problems

hi my name is ernesto and i own a 1982 300 ds and my turn signals stopped working I replaced all the relays in the fuse box and that did not take care of the problem. Does any body have any suggestion thanks
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Old 09-28-2006, 11:22 AM
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Location: Conway SC
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Default RE: 1983 300SD electrical problems

Try the relay and i am not sure if what makes MBs lights flash but american cars have a device called at flasher and the clicking sound u here could be that it has gone bad. Also the stalk in the steering colum could have gone bad i have heard that it can happen simply the wearing out from being turned on and off all the time. That could explain why the hazards work yet the turn signnals don't.
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Old 09-29-2006, 12:13 AM
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Posts: 157
Default RE: 1983 300SD electrical problems

Sometimes just pressing the 4 way flasher repeatedly on/off will restore the turn signals. power is routed thru the 4 way flasher switch for turn signal operation. the contacts inside the switch get dirty. I had a pinched wire inside the taillight housing (pinched it changing a bulb!) that blew the fuse for dash lights and taillight operation. Dash illumination not working/working is almost always the reostat being worn out. Each time the tripmeter is reset, the dash illumination might not work the next time. try gently rotating the **** to see if dash lights flicker on/off? Do a "search" for reostat. alot of people simply solder a jumper wire across it rather than replace it. When the speedo cluster is removed, you will see many brown wires terminating at the dash brace over the steering column. Make sure they are clean and very tight.
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Old 10-05-2006, 10:52 AM
Join Date: Sep 2006
Posts: 7
Default RE: 1983 300SD electrical problems

I just went thru and straightened out most of my dash issues out. Mainly lights not working etc. With the rehostat I just sprayed a bunch of contact cleaner into it and rotated it back and force. This took care of the all the instument lighting including shifter select and enviromental controls. I found most of my indicator bulbs to be good but the sockets to be corroded. So once again contact cleaner and small peice of light emery cloth did wonders. My last issues are a non working tach which I believe the problem to be in the engine compartment, glow plug indicator which is in the glow plug timer as the light works when you feed 12V from the GP timer to the light circuit and a non functioning odometer which I have the same issue as the repair described at www.Dieselgiant.com (invaluable site). That's one of those repairs that you have to start with a nice neat open bench and lots of time to work on that one tedious problem..... So that will be a while. Now if I could just find the starter interupt relay I'd be a happy camper. It's getting old starting it in neutral.

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Old 10-06-2006, 11:52 AM
Join Date: Mar 2005
Posts: 35
Default RE: 1983 300SD electrical problems

The Flasher for the turn signals is located under the center console up by the stick shift. Remove the ash tray and then remove the consol cover by lifting and pushing toward the rear of the car. There is a silver flasher relay mounted on a clip just forward of the shifter.

On some of the models the flasher is built into the emergency flasher button/flasher. If your car has a big red 1x2 inch emergency flasher button mounter in the console then that is the flasher. If your car has a smallish rocker switch for the emergency flashers then it will have the flashe/relay mounted in front of the shifter.

As for the other electrical problems; these older 123 series cars seem to have a few issues. The fuse block can cause all manner of grief. Over on buymbparts.com they have a fuse kit that has all the brass coated fuses that helps stop the corrosion between the fuse and the tabs in the fuse box. I've fixed many electrical issues by pulling the box, cleaning all the connections, replacing all the fuses and reinstalling. It sounds harder than it is. The other issues I've faced have been bad grounds. Remove, clean really well and reinstall as many ground wires as you can find (there are several). Again, not hard but it takes a little time. Grab a few beers, turn the ballgame on on the radio and make an afternoon of it.

Those two tips have fixed almost all of the electrical issues I've had in the past.

Good luck,
Tony T
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Old 09-18-2007, 07:50 PM
Join Date: Sep 2007
Posts: 3
Default RE: 1983 300SD electrical problems

ahhhhh!!! help my 92 300sd is crazy. i turn the turn signal on and all the lights in console start flashing.
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fix flashers and signal lights of 1983 mercedes 300 - Local SmartShopping This thread Refback 03-10-2013 06:30 PM
What is MERCEDES BENZ 300SD FLASHER UNIT? This thread Refback 02-19-2013 05:33 PM

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1983, 300, 300sd, 82, 83, benz, flasher, fuse, hazards, mercedes, rear, relay, remove, signals, speedo, turn, work

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